An old one and a bit all over the place. Still, plenty of interesting advice and insights.

This piece is a bit too much written as Rust zealotry for my taste. That being said, there's in my opinion an interesting core truth hidden in there: for now it seems to better foster "expert generalists" when investing in it. Now it might be just for now and might stop later... time will tell.

I mostly agree with this. I'd just complete it a bit: it's probably a good idea to have at least one language where you went really deep in (emphasis on at least). A kind of strategy to aim at "T shaped skills" (or better "paint drip shaped skills").

This rings true to me. What a messy path to get better at our craft!